I have a 2004 GXP w/o a CD changer. I can't find an aftermarket unit to work in vehicle.
I also tried to have dealer install a factory unit w/o success.
Any Help ? ! ?

your dealer wouldn't help you? My brother deals with GM factory Cd decks and CD changers. I'll see what he can do for you -and I can gauruntee it'll be cheaper than the dealer.
Also, if you can get the part # go to www.gmpartsdirect.com if you want a new one (plus this website also gives discounts up to 60% off the dealer price) . Also verify that your car has the CD changer cable installed already -if not you'll want the part # for that also.
PM or e-mail me if you want my brothers contact info.
TTYL,
Martin

I believe the factory CD changer (trunk mount) is made by Pioneer. I can't believe a dealer can not set you up with one.

Here'* the story... I purchased vehicle w/o CD changer and ordered same from dealer. Upon arrival of GM changer the dealer tried to install same and told me it was not possible to install. Evidently the cable from front to trunk is not installed and I have tried several independant installers to install a JVC 1500RF changer and they say there is no place to hookup the antenna to the radio.

I believe my brother has factory GM/Delco CD changer harness'*, but I'll see if he has one for your application.

<EDIT>

Just got off the phone from talking to Matt (brother) and he said he'd never heard of a CD changer harness that could be put in a Y2K+ Bonneville/Pontiac with the 2-din stereo.
Sounds like you might look into purchasing a MP3 player with a FM modulator, and start down-loading songs or turning your CD'* into MP3 format on your computer and throwing them onto the MP3 player.

Thanks for your help. There seems to be a problem starting in 2004. I had a 2000 SSEi and had a JVC changer installed. Then I had a 2003 Aurora and had same changer installed. Both these cars used the adapter to install in the upper right corner of the headliner area. The problem with the 2004 is the area in question is not available.
I do appreciate your help.